Evaluation of the single cervical skin test and interferon gamma responses to detect Mycobacterium bovis infected cattle in a herd co-infected with Mycobacterium avium subsp. paratuberculosis

Juan Seva*, Jose M. Sanes, Guillermo Ramis, Alberto Mas, Juan J. Quereda, Bernardo Villarreal-Ramos, David Villar, Francisco J. Pallares

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (SciVal)

Abstract

This study reports the performance of the single intradermal tuberculin (SIT) test and the interferon-gamma (IFN-γ) assay for Mycobacterium bovis in a cattle herd with high prevalence of paratuberculosis (PTB). A total of 58/350 animals were selected for necropsy based on one or more of the following criteria: positive to SIT, IFN-γ, a breeding cow that seroconverted to PTB and showed signs compatible with a wasting disease. Infection status was determined by post mortem diagnostic tests that included histopathology examination, mycobacterial cultures and PCR identification for M. bovis and Mycobacterium avium subsp. paratuberculosis (MAP). In 7/58 animals primary tuberculosis (TB) lesions, affecting only the retropharyngeal and/or mediastinal lymph nodes, were found; 3/7 animals were found SIT positive. PTB was confirmed in 35/58 animals, of which 30 had seroconverted and 14 had typical clinical signs. 45/58 animals were IFN-γ+ using the most stringent criterion (cut-off point≥0.05); however, IFN-γ test was only positive in 33 animals when using a higher threshold (cut-off point≥0.1). Three animals co-infected also showed extensive TB and diffuse PTB lesions. These results show that the combined use of SIT and IFN-γ, as interpreted using official guidelines, detected all confirmed cases of TB. Individually, the sensitivity of the SIT was inadequate to diagnose TB-positive animals with an advanced stage of PTB. The large number of IFN-γ+ animals with no visible TB lesion could be due, in part, to some protection conferred by prior infection with MAP.

Original languageEnglish
Pages (from-to)139-146
Number of pages8
JournalVeterinary Microbiology
Volume171
Issue number1-2
Early online date03 Apr 2014
DOIs
Publication statusPublished - 01 Jun 2014

Keywords

  • Cattle
  • IFN-γ
  • Mycobacterium avium subsp. paratuberculosis
  • Mycobacterium bovis
  • Paratuberculosis
  • Single cervical skin test
  • Tuberculosis

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